Closed Spinal Dysraphism and Tethered Cord

ACNRSO14_Layout 1 04/09/2014 22:14 Page 28 NEUROSURGERY ARTICLE Ruth-Mary deSouza trained in medicine at Closed Spinal Dysraphism Guy’s, Kings and St Thomas Medical School and graduated in 2008. She entered the London and Tethered Cord Neurosurgery training programme in 2010 and is currently an ST5 trainee on the South Thames Syndrome: A Review of Neurosurgery programme. David Frim Multidisciplinary Team Management is Professor of Surgery, Neurology and Paediatrics at the University of Chicago. He is an Summary internationally recognised • Embryology of spinal dysraphism clinical Neurosurgeon and Neurosciences Researcher • Clinical features of tethered cord syndrome who specialises in the care • Multidisciplinary management of closed spinal dysraphism of children and adults with congenital neurosurgical problems. Currently, Dr Frim serves as principal investigator on laboratory studies related to neural injury and clinical studies focusing on Abstract outcomes after treatment of congenital anomalies of the nervous system especially as related to cognition. The initial diagnosis as well as the long term management of occult spinal dysraphism and Dr Frim is joint senior author of the article. tethered spinal cord is often managed by a large number of healthcare professionals including Paediatricians, GPs, Neurologists, Neurosurgeons, Rehabilitation Physicians and Paige Terrien Church Therapists. We review the entity of spinal dysraphism. An approach to the evaluation and is an Assistant Professor of diagnosis of these entities is subsequently discussed. In addition, concepts involved in the Paediatrics at the pathophysiology, neurosurgical repair, and outcome are presented in the context of postop - University of Toronto. She is the Director of the erative management issues that rely upon the knowledge of all professionals who may Neonatal Follow Up Clinic encounter these patients. at Sunnybrook Health Sciences Centre and the Introduction Developmental Behavioral Physician Lead in the Spina The finding of a midline spinal anomaly in a child typically prompts referral to the Paediatric Bifida clinic at Holland Neurosurgeon for the evaluation of an occult spinal dysraphic state. Unfortunately, occult Bloorview Kids spinal dysraphism is not always readily apparent on physical examination, but is often diag - Rehabilitation Hospital. Dr Church is board certified nosed retrospectively after the child presents with neurologic, urologic, and orthopaedic find - through the American Board of Paediatrics in Neonatology, and Developmental Behavioral ings. In this article, we review the pathology and pathophysiology of occult spinal dysraphism Paediatrics and is interested in long-term functional and its relationship to the clinical entity of the tethered cord syndrome. Subsequently, outcomes of infants with neurologic conditions. concepts in the surgical and biopsychosocial management of children born with these defects will be discussed, in the context of management by the multidisciplinary team Tony Elias including Neurologists, GPs, Paediatric Surgeons, Physiotherapists and Neurorehabilitation MCh, FRCS has been Specialists. trained in Neurosurgery in India, and has obtained Fellowship in Definitions Paediatric Neurosurgery Spinal dysraphism is an umbrella term that describes any anomaly of the spinal cord, cauda from Great Ormond Street equina or overlying tissues such as vertebrae, muscles and skin. The nervous system abnor - Hospital, London and mality may or may not have associated mesenchymal or dermal changes. 1,2,3 Spinal Spinal Fellowship from National Hospital for dysraphism is essentially an anatomical term describing a spectrum of lesions and associ - Neurology and ated pathology – tethered cord is the clinical manifestation of the anatomical abnormalities Neurosurgery, London. He that constitute spinal dysraphism. Spinal dysraphism, also called spina bifida, can be subdi - is a Consultant Paediatric Neurosurgeon at Kings vided into two groups: open/aperta and closed/occulta. Closed spinal dysraphism describes College Hospital, London, and specialises in Paediatric Spinal Pathologies, including Spina Bifida. lesions with intact skin that are usually incidentally discovered on radiographic or physical exam. It is characterised by a disruption in the spinous processes and laminae Correspondence to: (mesenchymal structures) without herniation of underlying abnormal or normal neural Ruth-Mary deSouza, structures through the overlying skin. However open dysraphic lesions require emergent Department of Neurosurgery, King’s College Hospital, Denmark Hill, London, SE5 9RS UK. surgical repair to prevent infection, and are comprised of a broad spectrum of abnormali - ties. Table 1 summarises the key features of some open and closed dysraphic defects. Conflict of interest statement: The spectrum of spinal dysraphism can also be classified according to the point in spinal No author has a conflict of interest to declare. cord embryological development that the abnormality occurs, which will be described in Provenance and peer review: the following section on embryology of spinal dysraphism and in Figure 1. Submitted and internally reviewed. Embryology To cite: In order to understand the mechanism by which spinal dysraphism occurs, it is important deSouza RM, Church P, Elias T, Frim D. ACNR 2014;14(4):28-33. to appreciate the normal embryology of spinal cord development. This is split into three key stages and at each stage abnormalities can arise that give rise to dysraphic lesions. Essentially closed spinal dysraphism is believed to be a problem of secondary neurulation (the third stage of spinal development) whilst open dysraphism is a problem earlier on, during primary neurulation. 28 > ACNR > VOLUME 14 NUMBER 4 > SEPTEMBER/OCTOBER 2014 ACNRSO14_Layout 1 05/09/2014 12:34 Page 29 NEUROSURGERY ARTICLE Table 1 – Summary of key open and closed dysraphic conditions Open dysraphic defects Myelomeningocele Abnormal spinal cord exposed in the midline via defect in the posterior vertebral elements, fascia and skin Meningocele Herniation of the meninges via defect in the posterior vertebral elements and fascia. but covered by skin. The cord is not involved. Anencephaly Failure of anterior neuropore to close leads to herniation of a poorly developed brain – not compatible with life Rachischisis Midline defect with no underlying cord. Associated with anencephaly Open dysraphism in the majority of cases is associated with Chiari 2 malformation and hydrocephalus that may require CSF diversion Closed dysraphic defects Thickened filum terminale Filum more than 2 mm in diameter and containing abnormal tissue such as fat and fibrous bands Conus lipoma Intradural lipoma attached to the distal cord Lipomyelomeningocele Intradural lipoma attached to the distal spinal cord with the lipoma extending out of the spinal canal owing to a focal expansion of CSF space. Can be felt as a subcutaneous lipoma due to bony defect Diastematomyelia Bony spur dividing the cord into two separate cords in their own dural sleeves (type 1) or one dural sac (Split Cord malformation) and one cord split by a fibrous band (type 2) Terminal myelocystocele Expansion of the distal end of the central canal leading to an intergluteal closed cystic swelling. Dermal sinus tract Epithelialised tract opens on to the skin and which may extend to the intradural space. Can have associated dermoid or epidermoid Neurenteric cyst Cysts usually in the intradural extramedullary plane, lined with gastrointestinal or respiratory epithelium (endodermal origin). Can also be cranial Anterior and lateral They are very rare, and are protrusions of one or more layers of the thecal sac through a defect in the meningoceles vertebrae; may be associated with Currarino’s triad. Figure 1 – flow chart summarising the aberrant processes and time points in spinal cord development that can lead to spinal dysraphism. Stage of spinal cord development Adapted from Thompson et al, 2014 with permission [1] Disorder of gastrulation Disorder of primary neurulation Disorder of dysjunction Disorder of secondary neurulation Neurenteric cysts Myelomeningocele Dermal sinus tract Thickened filum Anterior and lateral meningocele Meningocele Lipomyelomeningocele Myelocystocele Diastematomyelia Anencephaly Cord lipoma Closed defects Open defects Closed defects Closed defects Embryology of the normal spinal cord dermal folds that fuse at the anterior and poste - Development of the normal spinal cord may rior neuropores as well as additional midline be understood by viewing it as a three stage fusion points to form the brain (rostral end) process: gastrulation, primary neurulation and and spinal cord (caudal end). This newly secondary neurulation. formed primitive central nervous system from Gastrulation refers to the initial formation of the process of ectodermal fusion then under - a trilaminar plate that contains all three of the goes “dysjunction” – physical separation from germ cell layers (ectoderm, mesoderm and the rest of the ectoderm which then goes on to endoderm) from which all future tissues will become skin. After dysjunction of neural tissue be derived. Ectoderm will give rise to the from the remainder of the ectoderm that is central nervous system and skin, endoderm to destined to be skin, the process of secondary the viscera; and mesoderm to the musculo- neurulation (essentially caudal spinal develop - skeletal system. During gastrulation, the primi - ment) can begin. tive streak of the embryo gives way to develop

Load more